Polymerizable ionic liquid comprising multifunctional cation and antistatic coatings

ABSTRACT

A multifunctional polymerizable ionic liquid is described comprising an anion and a cationic group having at least two ethylenically unsaturated polymerizable groups, each bonded to the cationic group via a divalent non-alkyl linking group. The multifunctional linking groups independently comprise a heteroatom such as oxygen or nitrogen. The linking groups may independently comprise one or more linkages such as an amide, urea, and more typically a urethane or ester linkage. The ethylenically unsaturated polymerizable groups are typically (meth)acrylate groups. Coatings and coated articles are also described.

RELATED APPLICATION DATA

This is a continuation of application Ser. No. 13/380,252, filed Dec.22, 2011, which is a national stage filing under 35 U.S.C. 371 ofPCT/US2010/046411, filed Aug. 24, 2010, which claims priority to U.S.Provisional Application No. 61/237,992, filed Aug. 28, 2009 and U.S.Provisional Application No. 61/289,072, filed Dec. 22, 2009, thedisclosures of which are incorporated by reference in their entiretyherein.

BACKGROUND

Ionic liquids (ILs) are salts in which the cation and anion are poorlycoordinated. At least one of the ionic components is organic and one ofthe ions has a delocalized charge. This prevents the formation of astable crystal lattice, and results in such materials existing asliquids, often at room temperature, and at least, by definition, at lessthan 100° C. For example, sodium chloride, a typical ionic salt, has amelting point of about 800° C., whereas the ionic liquidN-methylimidazolium chloride has a melting point of about 75° C.

Ionic liquids typically comprise an organic cation, such as asubstituted ammonium or a nitrogen-containing heterocycle, such as asubstituted imidazolium, coupled with an inorganic anion. However,species have also been described wherein the cation and anion areorganic. When the ionic liquid comprises at least one polymerizablegroup, such ionic liquid is a polymerizable ionic liquid (“PIL”).

SUMMARY

Although various polymerizable ionic liquids have been described,industry would find advantage in new multifunctional polymerizable ionicliquids.

In one embodiment, a multifunctional polymerizable ionic liquid isdescribed comprising an anion and a cationic group having at least twoethylenically unsaturated polymerizable groups, each bonded to thecationic group via a divalent non-alkyl linking group. Themultifunctional linking groups independently comprise a heteroatom suchas oxygen or nitrogen. The linking groups may independently comprise oneor more linkages such as an amide, urea, or ether linkage and moretypically a urethane or ester linkage. The ethylenically unsaturatedpolymerizable groups are typically (meth)acrylate groups.

In another embodiment, an (e.g. antistatic) coating is describedcomprising any of the multifunctional polymerizable ionic liquidsdescribed herein alone or in combination with other (meth)acrylatecomponents such as a monofunctional (e.g. mono(meth)acrylate)polymerizable ionic liquid.

In yet another embodiment, a coated substrate is described comprising a(e.g. film) substrate and the coating described herein cured on asurface of the substrate.

In yet another embodiment, a multifunctional polymerizable ionic liquidcomprising an initiator is described, having an air to nitrogen curingexotherm ratio of at least 0.70. The polymerizable ionic liquidcomprises at least one ethylenically unsaturated polymerizable groupbonded to a cationic group via a divalent non-alkyl linking group. Whenthe multifunctional polymerizable ionic liquid has a sufficiently highair to nitrogen curing exotherm ratio, the polymerizable ionic liquidcan be cured in air, rather than requiring curing in the absence ofoxygen such as by curing in the presence of nitrogen.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

Presently described are polymerizable ionic liquids, comprising a cationand an anion that are poorly coordinated. Such polymerizable ionicliquids have a melting point (T_(m)) below about 100° C. The meltingpoint of these compounds is more preferably below about 60° C., 50° C.,40° C., or 30° C. and most preferably below about 25° C., for ease ofuse in various polymerizable compositions such as (e.g. antistatic)coatings with or without the aid of solvent carriers in the coatingformulation. Polymerizable ionic liquids having a melting point below25° C. are liquids at ambient temperature.

Suitable cationic groups, also known as onium salts, include substitutedammonium salts, substituted phosphonium salts, and substitutedimidazolium salts. The structures of the cations of such onium salts aredepicted as follows:

The anion may be organic or inorganic, and is typically a monovalentanion, i.e. having a charge of −1.

The polymerizable ionic liquids described herein comprise at least twopolymerizable groups, and thus are described as multifunctionalpolymerizable ionic liquids, rather than monofunctional polymerizableionic liquid having a single polymerizable group. The polymerizableionic liquids typically comprise two or three polymerizable groups. Thepolymerizable groups are ethylenically unsaturated terminalpolymerizable groups including (meth)acryl such as (meth)acrylamide(H₂C═CHCON— and H₂C═CH(CH₃)CON—) and (meth)acrylate(CH₂CHCOO— andCH₂C(CH₃)COO—). Other ethylenically unsaturated polymerizable groupsinclude vinyl (H₂C═C—) including vinyl ethers (H₂C═CHOCH—).

The polymerizable ionic liquid functional as a reactive monomer and thusis substantially unpolymerized in the curable (e.g. antistatic) coatingcomposition at the time the curable composition is applied to a (e.g.film) substrate. The curable composition hardens upon curing viapolymerization of the ethylenically unsaturated groups of themultifunctional polymerizable ionic liquid.

The multifunctional polymerizable ionic liquids described herein can becharacterized as having a multifunctional cation, having two or morepolymerizable groups, each bonded to the same cationic group via adivalent non-alkyl linking group. As used herein, linking groups referto the entirety of the chain of atoms between the (e.g. single) cationand ethylenically unsaturated terminal group. Although the linkinggroups may and often comprises lower alkyl segments, e.g. of 1 to 4carbon atoms, the linking groups further comprise other atoms within thecarbon backbone and/or other groups pendant to the (e.g. carbon)backbone. Most commonly, the linking groups comprise heteroatoms such assulfur, oxygen, or nitrogen, and more commonly oxygen or nitrogen. Thelinking groups may comprise linkages such as amide (—CONR—), urea(—RNCONR—) or ether (—COC—) linkages and more commonly urethane(—ROCONR—) or ester linkages (—COOR)—; wherein R is a lower alkyl of 1-4carbon atoms.

For embodiments wherein the cation is ammonium or phosphonium, thepolymerizable ionic liquid may have the general formula:

wherein:Q is nitrogen or phosphorousR¹ is independently hydrogen, alkyl, aryl, alkaryl, or a combinationthereof;R² is independently an ethylenically unsaturated group;L¹ is independently a linking group with the proviso that at least twoof the linking groups are not alkyl linking groups;m is an integer of 2 to 4;n is an integer of 0 to 2;and m+n=4; andX is an anion.

At least two of the linking groups, L¹, are preferably linking groupsthat comprise one or more heteroatoms such as nitrogen, oxygen, orsulfur. In favored embodiments, at least two of the linking groups, L¹comprise nitrogen or oxygen heteroatoms, such as linking groups thatcomprise an amide, urea, ether, urethane or ester linkage. The linkinggroup may comprise more than one of such linkages.

Although each terminal ethylenically unsaturated group, R², bonded toeach linking group can comprise a different ethylenically unsaturatedgroup, the terminal ethylenically unsaturated group, R², is typicallythe same ethylenically unsaturated polymerizable group, such as the samevinyl, (meth)acrylamide, or (meth)acrylate group.

In some embodiments, m is 3 and thus, the polymerizable ionic liquid isa trifunctional (e.g. tri(meth)acrylate) polymerizable ionic liquid. Inother embodiments, m is 2 and thus, the polymerizable ionic liquid is adifunctional (e.g. di(meth)acrylate) polymerizable ionic liquid.

In some embodiments, n is at least 1. R¹ is typically hydrogen or astraight-chain lower alkyl of 1 to 4 carbon atoms. However, R¹ mayoptionally be branched or comprise a cyclic structure. R¹ may optionallycomprise phosphorous, halogen, one or more heteratoms such as nitrogen,oxygen, or sulfur.

Illustrative examples of anions useful herein include various organicanions such as carboxylates (CH₃CO₂ ⁻, C₂H₅CO₂ ⁻, ArCO₂ ⁻), sulfates(HSO₄ ⁻, CH₃SO₄ ⁻), sulfonates (CH₃SO₃ ⁻), tosylates, and fluoroorganics(CF₃SO₄ ⁻, (CF₃SO₂)₂N⁻, (C₂F₅SO₂)₂N⁻, (C₂F₅SO₂)(CF₃SO₂)N⁻, CF₃CO₂ ⁻,CF₃C₆F₄SO₃ ⁻, CH₃C₆F₄SO₃ ⁻, tetrakis(pentafluorophenyl)borate). Theanion may alternatively be an inorganic anion such as ClO₄ ⁻,fluoroinorganics (PF₆ ⁻, BF₄ ⁻, AsF₆ ⁻, SbF₆ ⁻) and halides (Br⁻, I⁻,Cl⁻). In some embodiments, the anion is preferably a sulfonate. Suchillustrative anions lack ethylenically unsaturated groups and thus arenon-polymerizable anions.

Preferred polymerizable ionic species wherein the cation is ammoniuminclude:

These species just described can include various other anions, such as afluororganic anion.

For embodiments wherein the cation is imidazolium, the polymerizableionic liquid may have the general formula:

whereinX, R¹, L¹ and R² are the same as previously described;and d is an integer of 0 to 3.

Although the polymerizable groups are depicted as being bonded via thelinking group to the nitrogen atoms of the imidazolium cation, one orboth polymerizable groups can optionally be bonded via the linkinggroup, L¹, at other positions of the imidazolium ring.

A preferred polymerizable ionic species wherein the cation isimidazolium includes

Preferred multifunctional polymerizable ionic liquids exhibit a high airto nitrogen curing exotherm ratio, as can be measured by photo DSCaccording to the test method described in the examples. The air tonitrogen curing ratio is typically at least 0.70 or 0.75. In preferredembodiments, the air to nitrogen curing exotherm ratio is typically atleast the 0.80, 0.85, 0.90, or 0.95. Although the exemplifiedcompositions were cured in the presence of nitrogen, it has been foundthat when the air to nitrogen curing ratio is sufficiently high, thepolymerizable ionic liquid can advantageously be substantiallycompletely cured in air (i.e. an oxygen rich environment) rather thanrequiring curing in the absence of oxygen.

For embodiments wherein the composition is to be cured in air and themultifunctional polymerizable ionic liquid is combined with a differente.g. (meth)acrylate such as a monofunctional polymerizable ionic liquid,that exhibits a high air to nitrogen curing exotherm ratio, the air tooxygen curing exotherm ratio of the multifunctional polymerizable ionicliquid, described herein, may be even lower than 0.70. One suitablemonofunctional polymerizable ionic liquid that can be combined with amultifunctional polymerizable ionic liquid is(acryloyloxyethyl)-N,N,N-trimethylammoniumbis(trifluoromethanesulfonyl)imide) having an air to nitrogen curingexotherm ratio of about 0.98.

A completely cured (i.e. hardened) polymerizable ionic liquid is solidat 25° C. and is substantially free of uncured polymerizable ionicliquid. When uncured polymerizable ionic liquid is present it typicallyresults as a surface residue exhibiting a “wet” appearance. Minimalsurface inhibition not only provides more complete curing but alsominimizes the formation of a less cured oxygen inhibited surface layer.The extent of curing can be determined by various methods known in art.One common method is to determine the amount of uncured material bysolvent extraction. In preferred embodiments, the amount of uncuredextractable polymerizable ionic liquid is less than 10%, more preferablyless than 5%, and most preferably less than 1% by weight of the curedcomposition.

The polymerizable ionic liquids described herein can be made by severalmethods. One method includes reaction of a hydroxyl functional ionicprecursor with a polymerizable isocyanate such as depicted by thefollowing reaction scheme:

Commercially available starting materials includetris-(2-hydroxyethyl)-methyl ammonium methyl sulfate available from BASF(BASIONIC FS01), diethanolamine hydrochloride, 2-amino-1,3-propanediolhydrochloride, and tris(hydroxymethyl)aminomethane hydrochloride. Theionic product may be further reacted to exchange the anion using anionmetathesis as described in “Ionic Liquids”, Meindersma, G. W., Maase,M., and De Haan, A. B., Ullmann's Encyclopedia of Industrial Chemistry,2007.

Another method includes the reaction of a hydroxyl functional amineprecursor with a polymerizable isocyanate, followed by alkylation oracidification, such as depicted by the following reaction scheme:

Commercially available starting materials include diethanol amine,diisopropanol amine, N-methyldiethanol amine, N-ethyldiethanol amine,N-butyldiethanol amine, triethanol amine,1-[N,N-bis(2-hydroxyethyl)-amino]-2-propanol, triisopropanol amine,3-amino-1,2-propanediol, 3-(dimethylamino)-1,2-propanediol,3-(diethylamino)-1,2-propanediol, 3-(dipropylamino)-1,2-propanediol,3-(diisopropylamino)1,2,-propanediol, 2-amino-1,3-propanediol,2-amino-2-ethyl-1,3,-propanediol, 2-amino-2-methyl-1,3,-propanediol,tris(hydroxymethyl)amino methane,bis(2-hydroxyethyl)amino-tris(hydroxymethyl)methane,2,2-bis(hydroxymethyl)-2,2′,2″-nitrilotriethanol,N,N′bis(2-hydroxyethyl)-ethylenediamine,N—N—N′—N′-tetrakis(2-hydroxypropyl)-ethylenediamine,1,3-bis[tris(hydroxymethyl)-methylamino]propane,3-pyrrolidino-1,2-propanediol, 3-piperidino-1,2-propanediol, and1,4-bis(2-hydroxyethyl)-piperazine.

Useful alkylating agents include alkyl halides, sulfates, andphosphonate esters, such as methyl iodide, ethyl iodide, methyl bromide,ethyl bromide, dimethyl sulfate, diethyl sulfate, and dimethylmethylphosphonate. Useful acidification agents include carboxylic acids,organosulfonic acids, and organophosphonic acids and inorganic acidssuch as hydrochloric acid, hydrofluoric acid, hydrobromic acid,phosphoric acid, nitric acid and the like.

Another method includes the reaction of an amine with an acrylatecompound to give a polymerizable amine precursor, followed by alkylationor acidification, such as depicted by the following reaction scheme:

Commercially available starting materials include amines such asmethylamine, ethylamine, propylamine, butylamine, hexylamine,isopropylamine, isobutylamine, 1-methylbutylamine, 1-ethy propylamine,2-methylbutylamine, isoamylamine, 1,2-dimethylpropylamine,1,3-dimethylbutylamine, 3,3-dimethylbutylamine, 2-aminoheptane,3-aminoheptane, 1-methylheptyamine, 2-ethylhexylamine,1,5-dimethylhexylamine, cyclopropylamine, cyclohexylamine,cyclobutylamine, cyclopentylamine, cycloheptylamine, cyclooctylamine,2-aminonorbornane, 1-adamantanamine, allylamine,tetrahydrofurfurylamine, ethanolamine, 3-amino-1-propanol,2-(2-aminoethoxy)ethanol, benzylamine, phenethylamine,3-phenyl-1-propylamine, 1-aminoindan, ethylenediamine, diaminopropane,and hexamethylenediamine.

Another method, that provides a polymerizable ionic liquid containing anether linking group, includes the reaction of a hydroxyl functionalprecursor with a functionalized (meth)acrylate molecule such as depictedby the following reaction scheme:

Another method, that provides a polymerizable ionic liquid containing anamide linking group, includes the reaction of an amine functionalprecursor with a functionalized (meth)acrylate molecule such as depictedby the following reaction scheme:

Another illustrative method, that provides a polymerizable ionic liquidcontaining a urea linking group, is depicted by the following reactionscheme:

The polymerizable ionic liquids described herein, having amultifunctional cation (i.e. a cation having two or more ethylenicallyunsaturated groups) can be utilized in various polymerizablecompositions such as an antistatic coating useful for making anantistatic layer of an optical film.

In some embodiments, the antistatic coating is comprised of apolymerizable ionic liquid having a multifunctional cation, as describedherein, in the absence of any other ethylenically unsaturatedpolymerizable (e.g. (meth)acrylate) components.

In other embodiments, the antistatic layer comprises a combination of atleast one polymerizable ionic liquid having a multifunctional cation, asdescribed herein in combination with at least one monofunctional (e.g.mono(methacrylate)) polymerizable ionic liquid. In yet otherembodiments, the antistatic layer further comprises at least onepolymerizable silicone monomer, oligomer, or polymer. The polymerizableionic liquid(s) may be present in the antistatic layer at a weightpercentage of 1 to 99.95%, 10 to 60%, or 30 to 50%. The acrylatefunctional onium salts are preferred over the methacrylate onium saltsbecause they exhibit a faster and greater degree of cure.

In either embodiment, an initiator is typically added to themultifunctional polymerizable ionic liquid or to the mixture ofpolymerizable ingredients comprising at least one multifunctionalpolymerizable ionic liquid, as described herein. The initiator issufficiently miscible with the resin system to permit ready dissolutionin (and discourage separation from) the polymerizable composition. It isappreciated that anion of the polymerizable ionic liquid can affect thesolubility of the polymerizable ionic liquid, particularly with theinitiator systems. When the polymerizable ionic liquid includes afluororganic anion, care is taken to select an appropriate class andconcentration of initiator.

Typically, the initiator is present in the composition in effectiveamounts, such as from about 0.1 weight percent to about 5.0 weightpercent, based on the total weight of the composition.

In some embodiments, the multifunctional polymerizable ionic liquid orcomposition comprising such is photopolymerizable and the compositioncontains a photoinitiator (i.e., a photoinitiator system) that uponirradiation with actinic radiation initiates the polymerization (orhardening) of the composition. Such photopolymerizable compositions canbe free radically polymerizable. The photoinitiator typically has afunctional wavelength range from about 250 nm to about 800 nm.

Suitable photoinitiators (i.e., photoinitiator systems that include oneor more compounds) for polymerizing free radically photopolymerizablecompositions include binary and tertiary systems. Typical tertiaryphotoinitiators include an iodonium salt, a photosensitizer, and anelectron donor compound as described in U.S. Pat. No. 5,545,676(Palazzotto et al.). Iodonium salts include diaryl iodonium salts, e.g.,diphenyliodonium chloride, diphenyliodonium hexafluorophosphate, anddiphenyliodonium tetrafluoroboarate. Some preferred photosensitizersinclude monoketones and diketones (e.g. alpha diketones) that absorbsome light within a range of about 300 nm to about 800 nm (preferably,about 400 nm to about 500 nm) such as camphorquinone, benzil, furil,3,3,6,6-tetramethylcyclohexanedione, phenanthraquinone and other cyclicalpha diketones. Of these camphorquinone is typically preferred.Preferred electron donor compounds include substituted amines, e.g.,ethyl 4-(N,N-dimethylamino)benzoate.

Other suitable photoinitiators for polymerizing free radicallyphotopolymerizable compositions include the class of phosphine oxidesthat typically have a functional wavelength range of about 380 nm toabout 1200 nm. Preferred phosphine oxide free radical initiators with afunctional wavelength range of about 380 nm to about 450 nm are acyl andbisacyl phosphine oxides.

Commercially available phosphine oxide photoinitiators capable offree-radical initiation when irradiated at wavelength ranges of greaterthan about 380 nm to about 450 nm includebis(2,4,6-trimethylbenzoyl)phenyl phosphine oxide (IRGACURE 819, CibaSpecialty Chemicals, Tarrytown, N.Y.),bis(2,6-dimethoxybenzoyl)-(2,4,4-trimethylpentyl) phosphine oxide (CGI403, Ciba Specialty Chemicals), a 25:75 mixture, by weight, ofbis(2,6-dimethoxybenzoyl)-2,4,4-trimethylpentyl phosphine oxide and2-hydroxy-2-methyl-1-phenylpropan-1-one (IRGACURE 1700, Ciba SpecialtyChemicals), a 1:1 mixture, by weight, ofbis(2,4,6-trimethylbenzoyl)phenyl phosphine oxide and2-hydroxy-2-methyl-1-phenylpropane-1-one (DAROCUR 4265, Ciba SpecialtyChemicals), and ethyl 2,4,6-trimethylbenzylphenyl phosphinate (LUCIRINLR8893X, BASF Corp., Charlotte, N.C.).

Tertiary amine reducing agents may be used in combination with anacylphosphine oxide. Illustrative tertiary amines useful in theinvention include ethyl 4-(N,N-dimethylamino)benzoate andN,N-dimethylaminoethyl methacrylate. When present, the amine reducingagent is present in the photopolymerizable composition in an amount fromabout 0.1 weight percent to about 5.0 weight percent, based on the totalweight of the composition.

In some embodiments, the curable dental composition may be irradiatedwith ultraviolet (UV) rays. For this embodiment, suitablephotoinitiators include those available under the trade designationsIRGACURE and DAROCUR from Ciba Speciality Chemical Corp., Tarrytown,N.Y. and include 1-hydroxy cyclohexyl phenyl ketone (IRGACURE 184),2,2-dimethoxy-1,2-diphenylethan-1-one (IRGACURE 651),bis(2,4,6-trimethylbenzoyl)phenylphosphineoxide (IRGACURE 819),1-[4-(2-hydroxyethoxy)phenyl]-2-hydroxy-2-methyl-1-propane-1-one(IRGACURE 2959), 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)butanone(IRGACURE 369),2-methyl-1-[4-(methylthio)phenyl]-2-morpholinopropan-1-one (IRGACURE907), and 2-hydroxy-2-methyl-1-phenyl propan-1-one (DAROCUR 1173).

The photopolymerizable compositions are typically prepared by admixingthe various components of the compositions. For embodiments wherein thephotopolymerizable compositions are not cured in the presence of air,the photoinitiator is combined under “safe light” conditions (i.e.,conditions that do not cause premature hardening of the composition).Suitable inert solvents may be employed if desired when preparing themixture. Examples of suitable solvents include acetone anddichloromethane.

Hardening is affected by exposing the composition to a radiation source,preferably a visible light source. It is convenient to employ lightsources that emit actinic radiation light between 250 nm and 800 nm(particularly blue light of a wavelength of 380-520 nm) such as quartzhalogen lamps, tungsten-halogen lamps, mercury arcs, carbon arcs, low-,medium-, and high-pressure mercury lamps, plasma arcs, light emittingdiodes, and lasers. In general, useful light sources have intensities inthe range of 0.200-1000 W/cm². A variety of conventional lights forhardening such compositions can be used.

The exposure may be accomplished in several ways. For example, thepolymerizable composition may be continuously exposed to radiationthroughout the entire hardening process (e.g., about 2 seconds to about60 seconds). It is also possible to expose the composition to a singledose of radiation, and then remove the radiation source, therebyallowing polymerization to occur. In some cases materials can besubjected to light sources that ramp from low intensity to highintensity. Where dual exposures are employed, the intensity of eachdosage may be the same or different. Similarly, the total energy of eachexposure may be the same or different.

The multifunctional polymerizable ionic liquid or compositionscomprising such may be chemically hardenable, i.e., the compositionscontain a chemical initiator (i.e., initiator system) that canpolymerize, cure, or otherwise harden the composition without dependenceon irradiation with actinic radiation. Such chemically hardenable (e.g.,polymerizable or curable) composition are sometimes referred to as“self-cure” compositions and may include redox cure systems, thermallycuring system and combinations thereof. Further, the polymerizablecomposition may comprise a combination of different initiators, at leastone of which is suitable for initiating free radical polymerization.

The chemically hardenable compositions may include redox cure systemsthat include a polymerizable component (e.g., an ethylenicallyunsaturated polymerizable component) and redox agents that include anoxidizing agent and a reducing agent.

The reducing and oxidizing agents react with or otherwise cooperate withone another to produce free-radicals capable of initiatingpolymerization of the resin system (e.g., the ethylenically unsaturatedcomponent). This type of cure is a dark reaction, that is, it is notdependent on the presence of light and can proceed in the absence oflight. The reducing and oxidizing agents are preferably sufficientlyshelf-stable and free of undesirable colorization to permit theirstorage and use under typical conditions.

Useful reducing agents include ascorbic acid, ascorbic acid derivatives,and metal complexed ascorbic acid compounds as described in U.S. Pat.No. 5,501,727 (Wang et al.); amines, especially tertiary amines, such as4-tert-butyl dimethylaniline; aromatic sulfinic salts, such asp-toluenesulfinic salts and benzenesulfinic salts; thioureas, such as1-ethyl-2-thiourea, tetraethyl thiourea, tetramethyl thiourea,1,1-dibutyl thiourea, and 1,3-dibutyl thiourea; and mixtures thereof.Other secondary reducing agents may include cobalt (II) chloride,ferrous chloride, ferrous sulfate, hydrazine, hydroxylamine (dependingon the choice of oxidizing agent), salts of a dithionite or sulfiteanion, and mixtures thereof. Preferably, the reducing agent is an amine.

Suitable oxidizing agents will also be familiar to those skilled in theart, and include but are not limited to persulfuric acid and saltsthereof, such as sodium, potassium, ammonium, cesium, and alkyl ammoniumsalts. Additional oxidizing agents include peroxides such as benzoylperoxides, hydroperoxides such as cumyl hydroperoxide, t-butylhydroperoxide, and amyl hydroperoxide, as well as salts of transitionmetals such as cobalt (III) chloride and ferric chloride, cerium (IV)sulfate, perboric acid and salts thereof, permanganic acid and saltsthereof, perphosphoric acid and salts thereof, and mixtures thereof.

It may be desirable to use more than one oxidizing agent or more thanone reducing agent. Small quantities of transition metal compounds mayalso be added to accelerate the rate of redox cure. The reducing oroxidizing agents can be microencapsulated as described in U.S. Pat. No.5,154,762 (Mitra et al.). This will generally enhance shelf stability ofthe polymerizable composition, and if necessary permit packaging thereducing and oxidizing agents together. For example, through appropriateselection of an encapsulant, the oxidizing and reducing agents can becombined with an acid-functional component and optional filler and keptin a storage-stable state.

Compositions of this invention can also be cured with a thermally orheat activated free radical initiator. Typical thermal initiatorsinclude peroxides such as benzoyl peroxide and azo compounds such asazoisobutyronitrile.

The optical films having an antistatic coating as described herein arestatic dissipative and will dissipate 90% of a 5 kilovolt charge appliedto the front surface in less then 10 seconds and preferably less then 5second. Column 13 of U.S. Pat. No. 6,740,413 describes test methods forstatic dissipation and surface resistivity. The specific procedures usedhere are described in the experimental section. In some embodiments, thestatic decay time is no greater than 2 second. Some preferred antistaticagents provide static decay times of no greater than 0.5, 0.4, 0.3, 0.2,or 0.1 seconds.

Some advantages include that the antistatic layers disclosed herein (1)adhere well to a variety of optical films; (2) impart good antistaticproperties to the resultant optical device; (3) can be durable so as towithstand handling and manipulation as the optical device is used, e.g.,to manufacture a display device; and (4) are clear and colorless, makingthem well suited for various light management purposes as they can beused as is or have additional agents imparted therein to provide colorselection, haze, or other desired effect.

A preferred monofunctional (e.g. mono(methacrylate) polymerizable ionicliquid to be used in combination with the polymerizable ionic liquidhaving a multifunctional cation has the formula(R¹)_(a-b)G⁺[(CH₂)_(q)DR²]_(b)X⁻wherein X, R¹, and R² are the same as previously described;

G is nitrogen, sulfur or phosphorous;

a is 3 where G is sulfur and a is 4 where G is nitrogen or phosphorousthen;

b is 1;

q is an integer from 1 to 4; and

D is oxygen, sulfur, or NR wherein R is H or a lower alkyl of 1 to 4carbon atoms.

In some embodiments, in which G is included in the cycle, the onium salthas one of the following formulas:

In some embodiments, G is a nitrogen atom of an ammonium cation. In someembodiments, D is oxygen. Further, in some embodiments R¹ is a loweralkyl of 1 to 4 carbon atoms.

Illustrative examples of anions useful herein include the same anions aspreviously described.

Fluorochemical anions can be favored for antistatic coating. Thus, insome embodiments, the anion is a fluorochemical anion. In someembodiments, the anion of the polymerizable ionic liquid having amultifunctional cation, as described herein, is a fluorochemical anion.In other embodiments, the monofunctional polymerizable ionic liquid,that is employed in combination with the polymerizable ionic liquidhaving a multifunctional cation, is a fluorochemical anion. Someillustrative examples include —C(SO₂CF₃)₃, —O₃SCF₃, —O₃SC₄F₉, and—N(SO₂CF₃)₂. Due to availability and cost the following are oftenpreferred: —O₃SCF₃, —O₃SC₄F₉, and —N(SO₂CF₃)₂.

Representative examples of weakly coordinating fluoroorganic anionsuseful herein include such anions as fluorinated arylsulfonates,perfluoroalkanesulfonates, cyanoperfluoroalkanesulfonylamides,bis(cyano)perfluoroalkanesulfonylmethides,bis(perfluoroalkanesulfonyl)imides,cyano-bis-(perfluoroalkanesulfonyl)methides,bis(perfluoroalkanesulfonyl)methides, andtris(perfluoroalkanesulfonyl)methides; and the like.

Examples of suitable weakly coordinating fluoroorganic anions includethe following:

wherein each R_(f) is independently a fluorinated alkyl or aryl groupthat may be cyclic or acyclic, saturated or unsaturated, and mayoptionally contain catenated (“in-chain”) or terminal heteroatoms suchas N, O, and S (e.g., —SF₄— or —SF₅). Q is independently an SO₂ or a COlinking group and X is selected from the group QR_(f), CN, halogen, H,alkyl, aryl, Q-alkyl, and Q-aryl. Any two contiguous R_(f) groups may belinked to form a ring. Preferably, R_(f) is a perfluoroalkyl group, Q isSO₂ and each X is QR_(f).

If fluoroorganic anions are used, they can be either fully fluorinated,that is perfluorinated, or partially fluorinated (within the organicportion thereof) as desired. Fluoroorganic anions include those thatcomprise at least one highly fluorinated alkanesulfonyl group, that is,a perfluoroalkanesulfonyl group or a partially fluorinatedalkanesulfonyl group wherein all non-fluorine carbon-bonded substituentsare bonded to carbon atoms other than the carbon atom that is directlybonded to the sulfonyl group (preferably, all non-fluorine carbon-bondedsubstituents are bonded to carbon atoms that are more than two carbonatoms away from the sulfonyl group).

The fluoroorganic anion may be at least about 80% fluorinated (that is,at least about 80% of the carbon-bonded substituents of the anion arefluorine atoms). The anion may be perfluorinated (that is, fullyfluorinated, where all of the carbon-bonded substituents are fluorineatoms). The anions, including the preferred perfluorinated anions, cancontain one or more catenated (that is, in-chain) or terminalheteroatoms such as, for example, nitrogen, oxygen, or sulfur (e.g.,—SF₄— or —SF₅).

Organic and fluoroorganic anions include perfluoroalkanesulfonates,fluoroorganic anions with two or three sulfonate groups,bis(perfluoroalkanesulfonyl)imides, andtris(perfluoroalkanesulfonyl)methides; perfluoroalkanesulfonates andbis(perfluoroalkanesulfonyl)imides). Preferred anions for someembodiments are perfluorinated where all X's are QR_(f) and all Q's areSO₂, more preferably the anion is a perfluoroalkanesulfonate or abis(perfluoroalkanesulfonyl)imide, most preferably the anion is abis(perfluoroalkanesulfonyl)imide.

The fluoroorganic ions can provide greater solubility and compatibilityof the onium salt with the non-onium polymerizable monomers, oligomers,or polymers. This is important in providing a layer with good clarity,and good ion mobility which can improve the antistatic performance ofthe layer. Preferred anions include —C(SO₂CF₃)₃, —O₃SCF₃, —O₃SC₄F₉, and—N(SO₂CF₃)₂. More preferred anions, due to availability and cost are—O₃SCF₃, —O₃SC₄F₉, and —N(SO₂CF₃)₂, while the most preferred anion is—N(SO₂CF₃)₂.

Illustrative examples of polymerizable silicone monomers, oligomers, andpolymers can be obtained from Degussa under the TEGO® Rad group ofproducts. Especially useful polymerizable silicones are acrylatefunctional silicone polyethers, like TEGO™ Rad 2250.

The antistatic layers may also be made using polymerizableperfluoropolyether moiety-containing monomers, oligomers, or polymers,either instead of or in addition to the polymerizable silicone monomers,oligomers, and polymers discussed above. U.S. Patent Appln. Publn.2006/0216500A1 (Klun et al.) discloses the synthesis ofperfluoropolyether moiety containing urethane acrylates useful herein.U.S. Patent Appln. Publn. No. 2008/0124555 (Klun et al.) disclosesperfluoropolyether moiety containing urethane acrylates containingpoly(ethylene oxide) moieties case that would be useful herein. PCTWO2009/029438 (Pokorny et al.) discloses curable silicones withperfluoropolyether moiety containing urethane acrylates that would beuseful herein.

As will be known to those skilled in the art, surface matte coatings areoften useful in optical films and it may be desired to impart such matteproperties to antistatic coatings of the invention. The increased hazeand reduced clarity from a matte coating helps provide a more uniformdisplay, and hide optical defects from the underlying film stack andbacklight, especially in liquid crystal displays (LCDs). Various meansare available to provide a matte coating and are useful with the presentinvention.

A multiphase coating can have a matte surface structure generated fromimmiscible materials incorporated in the coating at the surface orwithin the bulk of the coating, e.g., entrainment of particles such aspolymethyl methacrylate beads in the coating. In some embodiments,particles with different refractive index from the bulk of the coatingcan be used to impart desired haze properties without necessarilyyielding a matte surface. Though useful particles can be of any shape,typically preferred particle shapes are often in the form of sphericalor oblong beads. Preferable particle sizes are generally about 0.1microns to about 20 microns in average diameter. Particles can be madefrom any material that is compatible with the coating. Some illustrativeexamples of suitable materials for particles include polymethylmethacrylate, polybutyl methacrylate, polystyrene, polyurethane,polyamide, polysilicone, and silica. Useful particles can be obtainedfrom Ganz Chemical, Sekisui Plastics Co., Ltd., and Soken Chemical &Engineering Co., Ltd, all of Japan.

Particularly when the polymerizable composition is employed for useswherein transparency is important (such as an antistatic layer for usewith optical films), the polymerizable ionic liquid(s) and optionalpolymerizable silicone content, as well as other components, if any,should be compatible in that they will mix and polymerize to formtransparent films.

In addition to the polymerizable ionic liquid(s) and polymerizablesilicone components described above, antistatic layers of the inventioncan be made from curable compositions further comprising polymerizablenon-silicone monomers, oligomers, or polymers. Such materials might beused to modify properties of the resultant layer, e.g., adhesion to theoptical film, flexibility, or other mechanical properties, opticalproperties, e.g., its haze, clarity, etc.; reduce cost, etc.

Some illustrative examples of polymerizable (i.e. non-silicon,non-onium) monomers, oligomers, or polymers useful herein include, forexample, poly (meth)acryl monomers selected from the group consisting of(a) mono(methacryl) containing compounds such as phenoxyethyl acrylate,ethoxylated phenoxyethyl acrylate, 2-ethoxyethoxyethyl acrylate,ethoxylated tetrahydrofurfural acrylate, and caprolactone acrylate, (b)di(meth)acryl containing compounds such as 1,3-butylene glycoldiacrylate, 1,4-butanediol diacrylate, 1,6-hexanediol diacrylate,1,6-hexanediol monoacrylate monomethacrylate, ethylene glycoldiacrylate, alkoxylated aliphatic diacrylate, alkoxylated cyclohexanedimethanol diacrylate, alkoxylated hexanediol diacrylate, alkoxylatedneopentyl glycol diacrylate, caprolactone modified neopentylglycolhydroxypivalate diacrylate, caprolactone modified neopentylglycolhydroxypivalate diacrylate, cyclohexanedimethanol diacrylate, diethyleneglycol diacrylate, dipropylene glycol diacrylate, ethoxylated (10)bisphenol A diacrylate, ethoxylated (3) bisphenol A diacrylate,ethoxylated (30) bisphenol A diacrylate, ethoxylated (4) bisphenol Adiacrylate, hydroxypivalaldehyde modified trimethylolpropane diacrylate,neopentyl glycol diacrylate, polyethylene glycol (200) diacrylate,polyethylene glycol (400) diacrylate, polyethylene glycol (600)diacrylate, propoxylated neopentyl glycol diacrylate, tetraethyleneglycol diacrylate, tricyclodecanedimethanol diacrylate, triethyleneglycol diacrylate, tripropylene glycol diacrylate; (c) tri(meth)acrylcontaining compounds such as glycerol triacrylate, trimethylolpropanetriacrylate, pentaerthyritol triacrylate, ethoxylated triacrylates(e.g., ethoxylated (3) trimethylolpropane triacrylate, ethoxylated (6)trimethylolpropane triacrylate, ethoxylated (9) trimethylolpropanetriacrylate, ethoxylated (20) trimethylolpropane triacrylate),propoxylated triacrylates (e.g., propoxylated (3) glyceryl triacrylate,propoxylated (5.5) glyceryl triacrylate, propoxylated (3)trimethylolpropane triacrylate, propoxylated (6) trimethylolpropanetriacrylate), trimethylolpropane triacrylate,tris(2-hydroxyethyl)isocyanurate triacrylate; (d) higher functionality(meth)acryl containing compounds such as pentaerythritol tetraacrylate,ditrimethylolpropane tetraacrylate, dipentaerythritol pentaacrylate,ethoxylated (4) pentaerythritol tetraacrylate, caprolactone modifieddipentaerythritol hexaacrylate; (e) oligomeric (meth)acryl compoundssuch as, for example, urethane acrylates, polyester acrylates, epoxyacrylates; polyacrylamide analogues of the foregoing; and combinationsthereof. Such compounds are widely available from vendors such as, forexample, Sartomer Company of Exton, Pa.; UCB Chemicals Corporation ofSmyrna, Ga.; Cytec Corporation, Cognis, and Aldrich Chemical Company ofMilwaukee, Wis. Additional useful (meth)acrylate materials includehydantoin moiety-containing poly(meth)acrylates, for example, asdescribed in U.S. Pat. No. 4,262,072 (Wendling et al.).

Optical Films

Typically, the optical film in a device of the invention will beselected from the group consisting of reflective polarizers (e.g.,so-called multilayer optical films or “MOFs” having regularly repeatinglayers of alternating refractive indices), brightness enhancement films,and diffuse reflecting polarizer films (sometimes referred to as “DRPFs”having multiphase structures with domains of alternating refractiveindices). One illustrative example of a reflective polarizer is VIKUITI™Dual Brightness Enhancement Film II (DBEF-II), commercially availablefrom 3M, and described in U.S. Pat. No. 7,345,137 (Hebrink et al.).Suitable prismatic brightness enhancement films (sometimes referred toas “BEFs”), also commercially available from 3M, are described in, e.g.,U.S. Pat. No. 5,771,328 (Wortman et al.), U.S. Pat. No. 6,280,063(Fong), and U.S. Pat. No. 6,354,709 (Campbell et al.) and U.S. PatentAppln. Publn. No. 2009/0017256 (Hunt et al.). Illustrative examples ofdiffuse reflecting polarizer films that can be used herein include thosedisclosed in U.S. Pat. No. 5,825,543 (Ouderkirk et al.). Illustrativeexamples of commercially available optical films suitable for use hereininclude VIKUITI™ Dual Brightness Enhanced Film (DBEF), VIKUITI™Brightness Enhanced Film (BEF), VIKUITI™ Diffuse Reflective PolarizerFilm (DRPF), VIKUITI™ Enhanced Specular Reflector (ESR), and VIKUITI™Advanced Polarizing Film (APF), all available from 3M Company.

As described in U.S. Pat. No. 5,175,030 (Lu et al.), and U.S. Pat. No.5,183,597 (Lu), a microstructure-bearing article (e.g. brightnessenhancing film) can be prepared by a method including the steps of (a)preparing a polymerizable composition; (b) depositing the polymerizablecomposition onto a master negative microstructured molding surface in anamount barely sufficient to fill the cavities of the master; (c) fillingthe cavities by moving a bead of the polymerizable composition between apreformed base (such as a PET film) and the master, at least one ofwhich is flexible; and (d) curing the composition to yield an array ofmicrostructured optical elements on the base. The master can bemetallic, such as nickel, nickel-plated copper or brass, or can be athermoplastic material that is stable under the polymerizationconditions, and that preferably has a surface energy that allows cleanremoval of the polymerized material from the master.

Useful base materials include, for example, styrene-acrylonitrile,cellulose acetate butyrate, cellulose acetate propionate, cellulosetriacetate, polyether sulfone, polymethyl methacrylate, polyurethane,polyester, polycarbonate, polyvinyl chloride, polystyrene, polyethylenenaphthalate, copolymers or blends based on naphthalene dicarboxylicacids, polycyclo-olefins, polyimides, and glass. Optionally, the basematerial can contain mixtures or combinations of these materials.Further, the base may be multi-layered or may contain a dispersedcomponent suspended or dispersed in a continuous phase.

For some microstructure-bearing products such as brightness enhancementfilms, examples of preferred base materials include polyethyleneterephthalate (PET) and polycarbonate. Examples of useful PET filmsinclude photograde polyethylene terephthalate and MELINEX™ PET availablefrom DuPont Films of Wilmington, Del.

Some base materials can be optically active, and can act as polarizingmaterials. Polarization of light through a film can be accomplished, forexample, by the inclusion of dichroic polarizers in a film material thatselectively absorbs passing light. Light polarization can also beachieved by including inorganic materials such as aligned mica chips orby a discontinuous phase dispersed within a continuous film, such asdroplets of light modulating liquid crystals dispersed within acontinuous film. As an alternative, a polarizing film can be preparedfrom microfine layers of different materials. The materials within thefilm can be aligned into a polarizing orientation, for example, byemploying methods such as stretching the film, applying electric ormagnetic fields, and coating techniques.

Examples of polarizing films include those described in U.S. Pat. No.5,825,543 (Ouderkirk et al.) and U.S. Pat. No. 5,783,120 (Ouderkirk etal.). The use of these polarizer films in combination with a brightnessenhancement film has been described in U.S. Pat. No. 6,111,696 (Allen etal.). Another example of a polarizing film that can be used as a baseare those films described in U.S. Pat. No. 5,882,774 (Jonza et al.).

One or more of the surfaces of the base film material can optionally beprimed or otherwise be treated to promote adhesion of the optical layerto the base. Primers particularly suitable for polyester base filmlayers include sulfopolyester primers, such as described in U.S. Pat.No. 5,427,835 (Morrison et al.). The thickness of the primer layer istypically at least about 20 nm and generally no greater than about 300nm to about 400 nm.

The optical elements can have any of a number of useful patterns. Theseinclude regular or irregular prismatic patterns, which can be an annularprismatic pattern, a cube-corner pattern or any other lenticularmicrostructure. A useful microstructure is a regular prismatic patternthat can act as a totally internal reflecting film for use as abrightness enhancement film. Another useful microstructure is acorner-cube prismatic pattern that can act as a retroreflecting film orelement for use as reflecting film. Another useful microstructure is aprismatic pattern that can act as an optical turning film or element foruse in an optical display.

One preferred optical film having a polymerized microstructured surfaceis a brightness enhancing film. Brightness enhancing films generallyenhance on-axis luminance (referred herein as “brightness”) of alighting device. The microstructured topography can be a plurality ofprisms on the film surface such that the films can be used to redirectlight through reflection and refraction. The height of the prismstypically ranges from about 1 to about 75 microns. When used in anoptical display such as that found in laptop computers, watches, etc.,the microstructured optical film can increase brightness of an opticaldisplay by limiting light escaping from the display to within a pair ofplanes disposed at desired angles from a normal axis running through theoptical display. As a result, light that would exit the display outsideof the allowable range is reflected back into the display where aportion of it can be “recycled” and returned back to the microstructuredfilm at an angle that allows it to escape from the display. Therecycling is useful because it can reduce power consumption needed toprovide a display with a desired level of brightness.

The microstructured optical elements of a brightness enhancing filmgenerally comprise a plurality of parallel longitudinal ridges extendingalong a length or width of the film. These ridges can be formed from aplurality of prism apexes. Each prism has a first facet and a secondfacet. The prisms are formed on base that has a first surface on whichthe prisms are formed and a second surface that is substantially flat orplanar and opposite first surface. By right prisms it is meant that theapex angle is typically about 90°. However, this angle can range fromabout 70° to about 120° and may range from about 80° to about 100°.These apexes can be sharp, rounded or flattened or truncated. Forexample, the ridges can be rounded to a radius in a range of about 4 toabout 7 to about 15 micrometers. The spacing between prism peaks (orpitch) can be about 5 to about 300 microns. The prisms can be arrangedin various patterns such as described in U.S. Pat. No. 7,074,463 (Joneset al.).

In optical devices of the invention using thin brightness enhancingfilms, the pitch is preferably about 10 to about 36 microns, and morepreferably about 17 to about 24 microns. This corresponds to prismheights of preferably about 5 to about 18 microns, and more preferablyabout 9 to about 12 microns. The prism facets need not be identical, andthe prisms may be tilted with respect to each other. The relationshipbetween the total thickness of the optical article, and the height ofthe prisms, may vary. However, it is typically desirable to userelatively thinner optical layers with well-defined prism facets. Forthin brightness enhancing films on substrates with thicknesses close toabout 1 mil (about 20 to about 35 microns), a typical ratio of prismheight to total thickness is generally between about 0.2 and about 0.4.In other embodiments, thicker BEF materials will be used, BEF materialsa 50 micron pitch and 25 micron thickness.

As will be understood by those skilled in the art, optical devices ofthe invention may be made using other kinds of optical layers or otherembodiments of MOF, BEF, or DRPF materials than those illustrativeexamples discussed above.

Outer layer antistatic coatings on brightness enhancement films shouldimpart minimal absorbance and color, so as not to interfere withbrightness enhancement properties of the films. The coatings mayincrease haze and reduce clarity to provide a uniform display, and hideoptical defects from the underlying film stack and backlight. Theyshould provide reasonable durability.

In perhaps the simplest embodiments, devices of the invention willcomprise an optical layer with antistatic layer as described herein onone surface thereof. In some embodiments, the optical device mightcomprise antistatic layers of the invention on each surface of theoptical layer, e.g., DBEF-II, wherein the antistatic layers may be thesame or may be optimized independently, e.g., PMMA beads in oneantistatic layer but not the other, etc.

EXAMPLES

The invention will be explained with reference to the followingillustrative examples. All amounts are expressed in wt. % unlessotherwise indicated.

Test Methods

Average static decay was determined using the following method. Sheetsof test materials were cut into 12 cm by 15 cm samples and conditionedat relative humidity (RH) of about 50% for at least 12 hours. Thematerials were tested at temperatures that ranged from 22-25° C. Thestatic charge dissipation time was measured according to MIL-STD 3010,Method 4046, formerly known as the Federal Test Method Standard 10113,Method 4046, “Antistatic Properties of Materials”, using an ETS Model406D Static Decay Test Unit (manufactured by Electro-Tech Systems, Inc.,Glenside, Pa.). This apparatus induces an initial static charge (AverageInduced Electrostatic Charge) on the surface of the flat test materialby using high voltage (5000 volts), and a field meter allows observationof the decay time of the surface voltage from 5000 volts (or whateverthe induced electrostatic charge was) to 10 percent of the initialinduced charge. This is the static charge dissipation time. The lowerthe static charge dissipation time, the better the antistatic propertiesare of the test material. All reported values of the static chargedissipation times in this invention are averages (Average Static DecayRate) over at least 3 separate determinations. Values reported as >60seconds indicate that the sample tested has an initial static chargethat cannot be removed by surface conduction and is not antistatic. Whenthe sample tested did not accept a charge of about 3000 volts or more,it was not considered to have charged sufficiently to be antistatic.

Materials

DBEF Film (Optical Layer):

In each example, VIKUITI™ Dual Brightness Enhancement Film II (or DBEFII) from 3M was used as the optical film. Such films can be produced asfollows:

A multilayer reflective polarizer film was constructed with firstoptical layers created from a polyethylene naphthalate and secondoptical layers created from co(polyethylene naphthalate) and skin layersor non-optical layers created from a cycloaliphaticpolyester/polycarbonate blend commercially available from EastmanChemical Company under the tradename “VM365” and additionally blendedwith Styrene-Acrylate copolymer “NAS30” available from NOVA Chemicals.

The copolyethylene-hexamethylene naphthalate polymer (CoPEN5050HH) usedto form the first optical layers is synthesized in a batch reactor withthe following raw material charge: dimethyl 2,6-naphthalenedicarboxylate(80.9 kg), dimethyl terephthalate (64.1 kg), 1,6-hexane diol (15.45 kg),ethylene glycol (75.4 kg), trimethylol propane (2 kg), cobalt (II)acetate (25 g), zinc acetate (40 g), and antimony (III) acetate (60 g).The mixture was heated to a temperature of 254° C. at a pressure of twoatmospheres (2×10⁵ N/m²) and the mixture was allowed to react whileremoving the methanol reaction product. After completing the reactionand removing the methanol (approximately 42.4 kg) the reaction vesselwas charged with triethyl phosphonoacetate (55 g) and the pressure wasreduced to one torr (263 N/m²) while heating to 290° C. The condensationby-product, ethylene glycol, was continuously removed until a polymerwith intrinsic viscosity 0.55 dl/g as measured in a 60/40 weight percentmixture of phenol and o-dichlorobenzene is produced. The CoPEN5050HHpolymer produced by this method had a glass transition temperature(T_(g)) of 85° C. as measured by differential scanning calorimetry at atemperature ramp rate of 20° C. per minute. The CoPEN5050HH polymer hada refractive index of 1.601 at 632 nm.

The above described PEN and CoPEN5050HH were coextruded through amultilayer melt manifold to create a multilayer optical film with 275alternating first and second optical layers. This 275 layer multi-layerstack was divided into 3 parts and stacked to form 825 layers. The PENlayers were the first optical layers and the CoPEN5050HH layers were thesecond optical layers. In addition to the first and second opticallayers, two sets of skin layers were coextruded on the outer side of theoptical layers through additional melt ports. VM365 blended with 22 wt %NAs30 was used to form the external set of skin layers. The constructionwas, therefore, in order of layers: VM365/NAS30 blend outer skin layer,825 alternating layers of optical layers one and two, VM365/NAS30 blendouter skin layer.

The multilayer extruded film was cast onto a chill roll at 5 meters perminute (15 feet per minute) and heated in an oven at 150° C. (302° F.)for 30 seconds, and then uniaxially oriented at a 5.5:1 draw ratio. Areflective polarizer film of approximately 150 microns (8 mils)thickness was produced.

This multilayer film was measured to have a haze level of 42% asmeasured with a Gardner haze meter. This multilayer film when exposed tothe thermal shock test (warp test) had an acceptable level of warp after100 hrs of thermal cycling from −35° C. to 85° C.

Synthesis of Polymerizable Ionic Liquids Having Multifunctional Cation

Preparation of PIL A

Step 1: Preparation of a Bis Hydroxyethylated Imidazolium Salt.

A solution of 1-(2-hydroxyethyl)imidazole (25.0 g, 0.22 mol, availablefrom Aldrich) and 2-bromoethanol (27.9 g, 0.22 mol, available fromAldrich) in ethanol (100 mL) was heated at reflux for 36 hours, thencooled to room temperature and the ethanol removed at reduced pressure.The remaining oil was extracted with 4 100 mL portions of methylenechloride, then concentrated under reduced pressure to leave the bishydroxyethylated imidazolium salt as an orange oil (50.1 g). NMRanalysis of the oil confirmed that the desired product had been formed.

Step 1: Preparation of the Bis Methacrylate Ionic Liquid

A mixture of the bis hydroxyethylated imidazolium salt from Step 1 (4.40g, 18.6 mmol), 2-isocyanatoethyl methacrylate (5.75 g, 37.1 mmol,available from Aldrich), and 1 drop (about 20 mg) of dibutyltindilaurate (available from Aldrich) in methylene chloride (50 mL) wasstirred at room temperature for 4 days. At this time the initiallyinsoluble salt had dissolved and analysis of the reaction mixture byinfrared spectroscopy showed that the initially present isocyanateabsorption at 2275 cm⁻¹ was gone. NMR analysis of a portion of thereaction product from which the methylene chloride had been removed atreduced pressure confirmed that the desired bis methacrylate had beenformed. The bis methacrylate was kept in the methylene chloride solutionand used as such.

Preparation of PIL B

A mixture of n-butylamine (0.993 g, 14 mmol, Aldrich) andmethacryloxyethyl acrylate (5.00 g, 27 mmol, prepared according to Klee,J. E., et. al., Macromol. Chem. Phys., 200, 1999, 517) was stirred atroom temperature for 24 hours. The intermediate product was a colorlessliquid.

Dimethyl sulfate (0.57 g, 4.5 mmol) was added to the intermediateproduct from above (2.00 g, 4.5 mmol) dropwise over 10 minutes. Themixture was stirred for 17 hours to give the final PIL product as athick liquid.

Preparation of PIL-C (“POS-2”)

Polymerizable Onium Salt 2 (POS-2): represented by the followingformula:

To a solution of tris-(2-hydroxyethyl)methylammonium methylsulfate(11.58 g, 0.04 mol, available from BASF), isocyanatoethyl methacrylate(19.58 g, 0.12 mol), and 2,6-di-tert-butyl-4-methylphenol (BHT, 0.020 g,available from Aldrich) in methylene chloride (50 mL) in a flask fittedwith a drying tube and a magnetic stirrer was added a drop of dibutyltindilaurate. The solution was cooled in an ice bath and stirred for 3hours, then allowed to warm to room temperature and stirring wascontinued for another 36 hours. Progress of the reaction was monitoredby infrared spectroscopy, observing the disappearance of the isocyanateabsorbtion. When reaction was complete the solvent was removed atreduced pressure yielding a very viscous liquid.

Preparation of PIL D

To a stirred, ice cooled solution of tris-(2-hydroxyethyl)methylammoniummethylsulfate (17.38 g, 0.06 mol), mono-2-(methacryloyloxy)ethylsuccinate (41.42 g, 0.18 mol, available from Aldrich), and4-dimethylaminopyridine (1.098 g, 0.009 mol, available from Aldrich) inethyl acetate (150 mL) was added dropwise over a 2 hour period asolution of 1,3-dicyclohexylcarbodiimide (DCC, 37.1 g, 0.18 mol,available from Aldrich) in ethyl acetate (150 mL). After the DCCsolution was added, the temperature of the reaction mixture was allowedto rise gradually to room temperature, and then the reaction was stirredfor 14 hours. Then 0.5 g of deionized water and 2.0 g of silica gel wereadded into the flask and the reaction mixture stirred for 1 hour. Themixture was then filtered and solvent removed from the filtrate atreduced pressure to yield a very viscous liquid product having a slightyellow color.

Preparation of PIL-E

To PIL-C (14.09 g, 0.0190 mol) was added 14.09 g of water in a 250 mLroundbottom flask, which was heated under air in a 55° C. bath. Thenlithium bis(trifluoromethanesulfonyl)imide, Li⁺⁻N(SO₂CF₃)₂ from 3MCompany, under the trade designation “HQ-115”, 6.82 g of 80% solidssolution in water (0.0190 mol) was added over 10 seconds, withprecipitation of a whitish solid, followed by addition of 0.78 g ofwater. The flask was removed from the flask and 50 g of methylenechloride was added to the reaction with stirring. The reaction wasallowed to separate in a separatory funnel, and the lower organic layerwas washed with 15.1 g water. The organic layer was again separated,dried over anhydrous magnesium sulfate, treated with 2 mg BHT, andconcentrated under air at a pressure of 380 mm at 53° C. to yield 13.2 gof a clear thick oil.

Alternative Preparation of PIL-E

To a solution of tris-(2-hydroxyethyl)methylammonium methylsulfate (50.0g, 0.182 mol, in 37.5 g water in a 250 mL flask in a 50 degree C. oilbath, was added lithium bis(trifluoromethanesulfonyl)imide (65.18 g of80% solids solution in water (0.182 mol) with stirring over 20 seconds,followed by 6.26 g water. After 3 min of stirring the reaction wasconcentrated on a rotary evaporator in a bath at up to 100° C. toprovide 101.75 g of

and Li+—OSO₃CH₃ as a clear liquid with a dispersed whitish solid. Thismaterial when homogeneous is 78.85% by weight of the quat salt.

To 50 g of the mixture from the previous reaction (0.0889 mol, 0.267 OHequivalents of (HOCH₂CH₂)₃N(CH₃)+—N(SO₂CF₃)₂) in a 2 necked 250 mLroundbottom equipped with overhead stirrer, was added 56.62 g methylenechloride. The flask was placed into a 40° C. oil bath under air, and onedrop of dibutyltin dilaurate. Next isocyanatoethyl methacrylate (41.40g, 0.267 mol) was added over 20 min. The reaction was monitored by FTIRfor the disappearance of the isocyanate peak at 2275 cm⁻¹, and wasjudged to be complete after 7 hours of reaction. To the room temperaturereaction was added 75 g of methylene chloride and 50 g of water withstirring. The reaction was allowed to separate in a separatory funnel,and the lower organic layer was dried over anhydrous magnesium sulfate,treated with 12 mg of BHT and concentrated under air at a pressure of380 mm at 53° C. for about 5 hours to yield 86.76 g of a clear thickoil.

Preparation of PIL-F

To PIL-D (15.74, 0.0173 mol) was added 15.74 g of water in a 125 mLroundbottom flask, which was heated under air in a 55° C. bath. Thematerial was not very soluble in the water, and the reaction consistedof a cloudy upper phase and a liquid lower phase. Then lithiumbis(trifluoromethanesulfonyl)imide, Li⁺⁻N(SO₂CF₃)₂, 6.20 g of 80% solidssolution in water (0.0173 mol) was added over 10 seconds, withprecipitation of a whitish solid, followed by addition of 5.84 g water.The reaction was stirred for 2 hours, then the temperature of the bathwas dropped to 40° C. Next, 50 g of methylene chloride was added to thereaction with stirring for 30 min. The reaction was allowed to separatein a separatory funnel, and the lower organic layer was washed with 25.0g water. The organic layer was again separated, dried over anhydrousmagnesium sulfate, and concentrated under air at a pressure of 280 mm at53° C. to yield 16.12 g of a slightly yellow, clear oil.

Determination of Air to Nitrogen Curing Exotherm Ratio:

The photo polymerization behavior of monomers under N2 and air wasexamined using differential scanning photocalorimetry (photo DSC). Thephoto DSC was a TA instrument (New Castle, Del.) with DSC module 2920.The light source was a mercury/argon lamp with an Oriel PN 59480 425 nmlong pass light filter. The light intensity was 3 mW/cm², measured usingan International Light light meter Model IL 1400 equipped with a ModelXRL, 340A detector. The photo curable samples contained 0.5%camphorquinone (Sigma-Aldrich), 1.0% ethyl4-(N,N-dimethylamino)benzoate(Sigma-Aldrich) and 1.0% diphenyl iodiumhexafluorophosphate as the photoinitiator package. A 10 mg cured samplewas used as a reference.

About 10 mg of the sample was weighed accurately for the testing with aHermetic Pan (aluminum sample pan) as the sample holder. The sampleswere equilibrated at 37° C. for 5 minutes, and then the light aperturewas opened to irradiate the sample. During irradiation the sampletemperature was held at 37° C. The total irradiation time was 30minutes. After 30 minutes, the aperture was closed and the samplemaintained at 37° C. for another 5 minutes. The samples were testedunder nitrogen and air atmosphere respectively.

The data was collected as heat output per unit weight (mW/g). The datawas analyzed using TA Thermal Solutions Universal Analysis software.

Monomers were run once under nitrogen, then an identical sample was rununder air. The DSC recorded the heat generation from the curing sampleduring exposure, and the area under the curve was integrated to givetotal Joules/gram. The heat generated when the sample was cured in airwas divided by the heat generated when the sample was cured in nitrogento give the curing ratio. A higher ratio represents less oxygeninhibition.

Testing Results for Photocuring a Multifunctional PIL and TriethyleneGlycol Dimethacrylate (TEGDMA, Available from Aldrich) by Photo DSC

sample Curing ratio (air/N2) PIL-C 0.97 TEGDMA 0.36Monofunctional Polymerizable Ionic Liquid Utilized in Combination withMultifunctional Polymerizable Ionic Liquid1. Polymerizable Onium salt 1 (POS-1) (CH₃)₃NCH₂CH₂OC(O)CH═CH₂⁺⁻N(SO₂CF₃)₂, -(Acryloyloxyethyl)-N,N,N-trimethylammoniumbis(trifluoromethanesulfonyl)imide

was prepared as follows: To a tared 5 L, 3-necked round bottom flaskequipped with overhead stirrer was charged 1486 g (79.1% solids inwater, 6.069 mol) AGEFLEX™ FA1Q80MC*500 and the contents were heated to40° C. To the flask was added, over about one minute, 2177.33 g (80%solids in water, 6.069 mol) HQ-115, followed by 597.6 g deionized water.After stirring for 1 hour, the reaction was transferred to a separatoryfunnel and the lower organic layer (2688.7 g) was returned to thereaction flask and washed with 1486 g deionized water at 40° C. for 30min. The lower layer (2656.5 g) was again separated from the aqueouslayer and place in a dry 5 L, 3-necked round bottom equipped withoverhead stirrer and stillhead, and air bubbler. To the flask was added2000 g acetone and the reaction was distilled at atmospheric pressureover 6 hours with an air sparge to azeotropically dry the product with ayield of 2591 g of a clear liquid, which slowly crystallizes to a solid;2. Polymerizable Onium salt 1 (“POS-3”)3-butyl-1-[2-(2-methyl-acryloyloxy)-ethyl]-3H-imidazol-1-ium bromide

A) Synthesis of 3-Butyl-1-(2-hydroxy-ethyl)-3H-imidazol-1-ium bromide

N-Butyl imidazole (freshly distilled. 37.2 g, 300 mmol) and2-bromoethanol (freshly distilled. 37.5 g, 300 mmol) were mixed at roomtemperature to cause a slightly exothermic reaction. The mixture washeated at 50° C. for 90 hours. A very viscous liquid was obtained asproduct.

B) Synthesis of3-butyl-1-[2-(2-methyl-acryloyloxy)-ethyl]-3H-imidazol-1-ium bromide

To 3-butyl-1-(2-hydroxy-ethyl)-3H-imidazol-1-ium bromide (29.9 g, 120mmol) was added 20 mg of BHT and 2-methacryloyl chloride (13.8 g, 132mmol). The starting ionic liquid (IL) was insoluble in 2-methacryloylchloride. The mixture was stirred at room temperature. The IL graduallydissolved and a uniform pink solution was obtained in about half anhour. Volatile side product and starting materials were removed undervacuum after 4 hours of reaction. A light brown liquid was obtained asproduct.

Examples 1 to 3

Three polymerizable clear coating formulations, having formulations asindicated, were prepared, coated on DBEF-II, dried, cured, and tested.These formulations all contained 85% methanol and 0.15% CIBA™ DAROCUR™4265 curing agent. Otherwise, they varied as shown in Table 1 below.Each formulation was mixed to ensure the soluble components weredissolved. Each formulation was further coated onto the back side ofDBEF-II with a #16 wire wound Meyer rod, to give an average drythickness of about 3 microns. Each coating was dried for 2 minutes in abatch oven at 140° F., and then UV cured in a nitrogen environment withtwo passes at 35 feet per minute, under a Fusion F600 Microwave drivenmedium pressure lamp using a D bulb, from Fusion UV Systems Inc. At aspeed of 35 fpm, the UV energy emitted is as follows: UVA 460 mJ/cm²,UVB 87 mJ/cm², UVC 12 mJ/cm², UVV 220 mJ/cm². All the coatings provideda smooth clear coating layer without interfering with the brightnessenhancement properties of the DBEF-II film.

The formulations and static decay results are as shown in Table 1wherein is seen the surprising and dramatic improvement of antistaticproperties in a polymerizable clear coating from the combination of apolymerizable onium ionic liquid, and a polymerizable silicone.

TABLE 1 PIL-C TEGO Rad 2250 Avg POS-1 (POS-2) polymerizable Static (wt-%(wt-% silicone Decay Example solids) solids) (wt-% solids) (Seconds)Example 1 0 14.9 g 0   4.8   (99%) Example 2 0 14.7 g 0.18 g 2.0 (97.8%)(1.2) Example 3 7.3 g  7.3 g 0.18 g 0.04 (48.9%) (48.9%) (1.2)

For Examples 4 and 5 the components as described in Table 2 weredissolved in 2.0 grams of methanol. Each formulation was coated onto PETfilm (available from Dupont under the trade designation “Melinex 618”)with a #12 wire wound Meyer rod, to give an average dry thickness ofabout 10 microns. Each coating was dried for 5 minutes in a batch ovenat 60° C., and then UV cured in a nitrogen environment with two passesat 30 feet per minute on a 6 inch UV curing process line equipped with aFusion UV H bulb (on high power 100% UV that provides 58 mJ/cm² at the30 feet per minute speed) from Fusion UV Systems Inc. All the curedcoatings provided a non-tacky smooth clear coating layer.

The cured coatings were tested as previously described except that thecured coatings were tested immediately at ambient humidity, averaging 2separate determinations.

TABLE 2 PIL - A PIL-C POS-3 Avg Static Surface (wt-% (wt-% (wt-% Darocur1173 Decay Resistance Example solids) solids) solids) Photoinitiator(Seconds) ohms/square Example 0.0 g 2.0 g 0.50 g 0.023 g 0.19 1.70 ×10¹¹ 4 (79.3%) (19.8%)  (0.9%) Example 3.0 g 0.0 g 0.25 g 0.023 g 0.022.60 × 10⁹  5 (91.7%) (7.6%) (0.8%)

Although the present invention has been fully described in connectionwith the preferred embodiments thereof with reference to theaccompanying drawings, it is to be noted that various changes andmodifications are apparent to those skilled in the art. Such changes andmodifications are to be understood as included within the scope of thepresent invention.

The patents and patent applications cited herein are all incorporated byreference in their entirety.

What is claimed is:
 1. A multifunctional polymerizable ionic liquidhaving the formula

wherein: Q is nitrogen or phosphorous; R¹ is independently hydrogen,alkyl, aryl, alkaryl, or a combination thereof; R² is independently anethylenically unsaturated group selected from (meth)acryl or vinylether; L¹ is the divalent linking group independently comprising one ormore linkages selected from amide, urethane, urea, or ester; m is aninteger of 2 to 4; n is an integer of 0 to 2; and m+n=4; X is an anion,wherein when n is 2, X is an organic anion.
 2. The multifunctionalpolymerizable ionic liquid of claim 1 wherein n is at least 1 and R¹ isa lower alkyl of 1 to 4 carbon atoms.
 3. The multifunctionalpolymerizable ionic liquid of claim 1 wherein R² is (meth)acrylate. 4.The multifunctional polymerizable ionic liquid of claim 1 wherein thepolymerizable ionic liquid has the formula


5. A multifunctional polymerizable ionic liquid wherein themultifunctional polymerizable ionic liquid has the formula

wherein: R¹ is independently comprises hydrogen, alkyl, aryl, alkaryl,or a combination thereof; R² is independently an ethylenicallyunsaturated group selected from (meth)acryl or vinyl ether; L¹ is thedivalent linking group independently comprising one or more linkagesselected from amide, urethane, urea, or ester; d is an integer of 0 to3; X is an anion.
 6. The multifunctional polymerizable ionic liquid ofclaim 1 wherein the polymerizable ionic liquid has an air to nitrogencuring exotherm ratio of at least 0.90.
 7. A coating comprising themultifunctional polymerizable ionic liquid of claim
 1. 8. The coating ofclaim 7 wherein the coating further comprises at least one polymerizablemonomer, oligomer, or polymer.
 9. The coating of claim 8 wherein thepolymerizable monomer, oligomer, or polymer is selected frompoly(meth)acryl monomers, mono(meth)acryl compounds, and oligomeric(meth)acryl compounds.
 10. The coating of claim 7 wherein the coatingcan be completely cured in air.
 11. A coated substrate comprising asubstrate and the coating claim 1 cured on a surface of the substrate.12. The multifunctional polymerizable ionic liquid of claim 5 whereinthe anion is a sulfonate or fluororganic anion.
 13. The coatingcomposition of claim 7 wherein the coating further comprises amonofunctional polymerizable ionic liquid.
 14. The coating of claim 13wherein the monofunctional polymerizable ionic liquid has the formula:(R¹)_(a-b)G⁺[(CH₂)_(q)DR²]X⁻ wherein each R¹ comprises independently ahydrogen, alkyl, aryl, alkaryl, or a combination thereof; G is nitrogen,sulfur or phosphorous; a is 3 where G is sulfur and a is 4 where G isnitrogen or phosphorous; q is an integer from 1 to 4; D is oxygen,sulfur, or NR wherein R is H or a lower alkyl of 1 to 4 carbon atoms; R²is a (meth)acryl; and X− is an anion.
 15. The coating of claim 14wherein G is nitrogen of an ammonium cation.
 16. The coating of claim 14wherein G is included in the cycle of an imidazolium cation and themonofunctional polymerizable liquid has the formula:


17. The multifunctional polymerizable ionic liquid of claim 5 whereinthe polymerizable ionic liquid has an air to nitrogen curing exothermratio of at least 0.90.
 18. A coating comprising the multifunctionalpolymerizable ionic liquid of claim
 5. 19. The coating of claim 18wherein the coating further comprises at least one polymerizablemonomer, oligomer, or polymer.
 20. The coating of claim 19 wherein thepolymerizable monomer, oligomer, or polymer is selected frompoly(meth)acryl monomers, mono(meth)acryl compounds, and oligomeric(meth)acryl compounds.
 21. The coating of claim 18 wherein the coatingcan be completely cured in air.
 22. A coated substrate comprising asubstrate and the coating claim 5 cured on a surface of the substrate.23. The coating composition of claim 18 wherein the coating furthercomprises a monofunctional polymerizable ionic liquid.
 24. The coatingof claim 23 wherein the monofunctional polymerizable ionic liquid hasthe formula:(R¹)_(a-b)G⁺[(CH₂)_(q)DR²]X⁻ wherein each R¹ comprises independently ahydrogen, alkyl, aryl, alkaryl, or a combination thereof; G is nitrogen,sulfur or phosphorous; a is 3 where G is sulfur and a is 4 where G isnitrogen or phosphorous; q is an integer from 1 to 4; D is oxygen,sulfur, or NR wherein R is H or a lower alkyl of 1 to 4 carbon atoms; R₂is a (meth)acryl; and X− is an anion.
 25. The coating of claim 24wherein G is nitrogen of an ammonium cation.
 26. The coating of claim 24wherein G is included in the cycle of an imidazolium cation and themonofunctional polymerizable liquid has the formula: